نتایج جستجو برای: bias
تعداد نتایج: 110381 فیلتر نتایج به سال:
اندازه گیری مستقیم زیست توده بسیار مشکل، پرهزینه و زمانبر است. در این موارد معمولاً از روش های برآورد زیست توده، ازجمله تکنیک های سنجش از دور استفاده می شود. هدف تحقیق حاضر، بررسی روش های مختلف مبتنی بر داده های ابر مکانی ماهواره quickbirdو استفاده از روش های سنجش از دوری، جهت تخمین زیست توده درختان در چهار گونه شامل کاج تهران (pinus eldarica)، سرو نقره ای (cupressus arizonica)، اقاقیا (robinia ...
A common hypothesis about practices to reduce survey nonresponse is that those persons brought into the respondent pool through persuasive efforts may provide data filled with measurement error. Two questions flow from this hypothesis. First, does the mean square error of a statistic increase when sample persons who are less likely to be contacted or cooperate are incorporated into the responde...
Most professional economists believe that economist in general are more selfish than other persons and that this greater selfishness is due to economic education. In this paper we offer empirical evidence against this widely held belief. Using a unique data set about giving behaviour to two social funds at the University of Zurich, it is shown that economic training does not make people act mor...
The most relevant practical impediment to an application of the Markowitz portfolio selection approach is the problem of estimating return moments, in particular return expectations. We analyze the consequences of using return estimates implied by analysts’ dividend forecasts under the explicit notion of taxes and non-flat term structures of interest rates and achieve quite good performance res...
This study compared various biased estimation and subset selection regression techniques over a wide range of realistic situations. In an attempt to make the results applicable to the class of all practical regression problems, the parameters relevant to a comparison of the techniques involved were varied systematically. An outline of the design follows. (1) The residual variance ((sigma)('2)) ...
This paper proposes a method to extend the current ISO Guide to the Expression of Uncertainty in Measurement to include the case of known, but uncorrected, measurement bias. It is strongly recommended that measurement results be corrected for bias, however in some situations this may not be practical, hence an extension of the Guide is proposed to address this special situation. The method keep...
We consider the implications of the definition of juror bias offered in Schwartz and Schwartz for optimal use of juror challenges to improve the accuracy of the jury process. For them, bias consists of a juror assinging more/less weight to the evidence for guilt than would be assigned by the median juror in a fully representative pool of jurors. When juror assessments of the evidence have a pro...
We prove that a subtle but substantial bias exists in a common measure of the conditional dependence of present outcomes on streaks of past outcomes in sequential data. The magnitude of this novel form of selection bias generally decreases as the sequence gets longer, but increases in streak length, and remains substantial for a range of sequence lengths often used in empirical work. We observe...
The aim of this study was to compare the educational achievement of female twins (n = 577) and their matched singleton controls (n = 447), who were selected from participants of a national test of educational achievement in the years 1993 to 1998. To assure the representativeness of the selected groups we also compared the achievement scores of the twins and the controls to those of the total D...
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